Shipps, Peredo and Pyenson 2018 report
on a Late Oligocene mammalodontid, the first from the Northern Hemisphere. “The skull and teeth of this specimen bear boreholes from bone-eating Osedax worms, providing valuable information on the taphonomy of the specimen. Critically, this specimen preserves intact ear bones and several teeth.”
Mammalodon (Fig. 1) is indeed in the lineage of mysticete whales, but several nodes distant (Fig. 2) in the large reptile tree. It is related to Janjucetus and Anthracobune, basal to desmostylians, not far from hippos. Desmostylians are also found along the Pacific rim, so this appearance of an ancestor in Washington state is expected. All are mesonychids, not ungulates.
Shipps BK, Peredo CM and Pyenson ND 2018. An unexpected Northerner with burrowed bones: a new mammalodontid (Mysticeti) from the Pacific Northwest with Osedax bores provides insight into Oligocene marine taphonomy and mysticete evolution. SVP abstracts.